Separation of acetylenes from hydrocarbon mixtures



Sept. 18, 1945. E, v. FASCE 2,384,902 SEPARATION OF ACETYLENES FROMHYDROCARB ON MIXTURES Filed April 9. 1943 OUTLfT T0 ABSORBER AID/OLEFl/V flecqyzny V ACTIONATN c SYSTEM TOWER I A cz'rxanz POL YMEROUTLET EXTRA cT/oN 7'0 wen.

H (7 RECOVERED .BUTANR suL-Funw. zsccvazy clanking TA Nl Patented Sept.18, 1945 SEPARATION OF ACETYLENES FROM HYDROGARBON BIIXTURES E i V.Fasce, Baton Rouge, La., assignor to Standard Oil Development Company, acorporation of Delaware Application April 9, 1943, Serial No. 482,366

3 Claims. ((1260-6815) This invention relates to improvements in theprocess for separating dioleiins from hydrocarbon mixtures containingdioleflns and acetylenes and relates particularly to the separation ofalkyl acetylenes before the diolefins are separated and segregated fromthe said hydrocarbon mixture.

The chief sources of, diolefins are hydrocarbon mixtures obtained bycracking petroleum oils. The craclred mixtures are first distilled toobtain fractions containing only olefin and paraflln hydrocarbons havingthe same number of carbon atoms to the molecule, for examples 4, 5, and6. All such fractions, for example one having 4 carhon atoms to themolecule, contain both the desirable diolefin and small traces of alkylacetylenes in concentrations that may range up to several thousand partsper million. For example, a carbon atom mixtures of hydrocarbonsobtained by pyrolyzing petroleum oils, by analysis, were found tocontain from 500 to 800 parts of alkyl acetylenes per million of oil.

Alkyl acetylenes react with the copper solution usedfor the extractionof diolefins and form compounds which may explode if the material isallowed to 'dry. Not only is it desirable to remove the alkyl acetylenesto avoid this hazard but the presence of the almrl acetylenes even insmall amounts in the dioleiins when used as a feed for the rubber unityields a product of inierior quality. Rubber prepared from dioleflnscontaining alkyl acetylenes has a very low tensile strength andtherefore it is essential that the alkyl acetylenes are first removedbefore the diolehills are separated from the hydrocarbon mixture andused in the manufacture of rubber.

An object of this invention is to provide means for the separation andremoval of alkyl acetyl-' ones from hydrocarbon mixtures before thediolefins are removed and without any substantial reduction in thediolefin content or the said hydrocarbon mixture.

be varied from 0 to 75 F. at pressures up to 100 lbs. per square inch.The ratio of hydrocarbon to solvent may be varied from about 1:8 toabout before the hydrocarbon mixture is treated with a selectiveabsorbent for the diolefins, for example 2:1. The hydrocarbon mixture,after the acetylenes have been removed, is washed with water to removethe last traces of sulfuryl chloride.

The following description when read with refence to the accompanyingdrawing will illustrate one embodiment of this invention. A mixture ofolefin and paraifin hydrocarbons is distilled into fractions having thesame number of carbon atoms to the molecule, that is, 4, 5, and 6. Theseparation of alkyl acetylenes from the fraction having 4 carbon atomsto the molecule will be used here as an example for illustration only asthe other fractions may be treated in a similar manner. 7

Referring to the drawing, number 1 designates a packed tower. othertypes of towers may be used such as onewith bubble caps, baiiies, etc.Into the lower part of tower I is passed by means of pipe 2 the C4fraction containing butadiene and which may have an alkyl acetylenecontent as high as 0.1 to 1%. In the upper part of tower i by means ofpipe 3 is passed a suliuryl chloride solution containing from 0.1 to 1%of an organic peroxide such as benzoyl peroxide. The two solutions arepassed in countercurrent flow and an alkyl acetylene free C4 hydrocarbonfraction is recovered through pipe 4.

The sulfuryl chloride solution containing the benzoyl peroxide oncontacting with the C4 hydrocarbon mixture effects the selective Pymerization oi the alkyl acetylenes. V acetylene polymers dissolved inthe sulfuryl chloride solution are removed from tower I by means of pipe5, which is provided with pump 8. The solution of the alkyl acetylenepolymers is passed to the upper part of extraction tower 'I. In thelower part oi. tower 1 through pipe 8 provided with pump 9 is passed alight paraflin hydrocarbon such as butane which butane flows incountercurrent relation to sulfuryi chloride dissolving out the alkylacetylenes. The butane with alkyl acetylenes in solution is removed fromtower l by means of pipe I! and passed to fractlonating tower ll. Towerll may be packed or provided with bubble caps, trays or otherwisearranged. Heat is supplied to the bottom of The alkyl' distilled. Thebutane vapors are passed from tower H through outlet pipe l3 andcondenser M to butane recovery tank IS. The butane may be recycledthrough pipe 8 to'tower l.

Sulfuryl chloride is withdrawn by pipe l6 provided with valve H fromextraction tower 'I and passed to storage tank l8 and may be recycledthrough pipe 3 to tower l. Alkyl acetylenes are removed to storage notshown from fractionating tower II by means of pipe I! provided withvalve 20. a

I claim:

1. In a process for separating a diolefin from a mixture of hydrocarbonscontaining a diolefln and an alkyl acetylene, the improvement whichcomprises contacting a, mixture of hydrocarbons containing a dioleflnand an alkyl acetylene with a sulfuryl chloride solution containing from0.1-1% of benaoyl peroxide, separating the sulfuryl chloride solutioncontaining from (Llof benzoyl peroxide and absorbed alkyl acetylene fromthe unabsorbed hydrocarbon, and contacting the residual unabsorbedhydrocarbons with a selected absorbent for the diolenns.

2. In a process for separating'a diolefln from a mixture of hydrocarbonscontaining a dlolefln and an alkyl acetylene, the improvement" whichcomprises contacting a mixture of hydrocarbons containing a diolefln andan alkyl acetylene with a sulturyl chloride solution containing from2,884,902" tower II by means of coil l2 and the butane is 0.1-1% ofbenzoyl peroxide, separating the suliuryl chloride solution containingfrom 0.14% of benzoyl peroxide and absorbed alkyl acetylene from theunabsorbed hydrocarbon and contacting the residual unabsorbedhydrocarbons with an ammoniacal cuprous acetate solution, separating theammonlacal cuprousacetate solution from the unabsorbed hydrocarbons andheating the said separated ammoniacal cuprous acetate solution torecover dioleiins.

3. In the separation of butadiene from a mixture of hydrocarbonsobtained by cracking petroleum oils and containing butadiene and alkylacetylene, the improvement which comprises contacting the mixture ofhydrocarbons obtained by cracking petroleum oils and containing butadienand alkyl acetylene with a sulfuryl chloride solution containing from0.1-1% of benzoyl peroxide, separating the sulfuryl chloride solutioncontaining the benzoyl peroxide and absorbed hydrocarbons from theunabsorbed hydrocarbons, contacting the separated sulfuryl chloridecontaining the benzoyl peroxide and the absorbed hydrocarbons with aliquid hydrocarbon which is volatile at room temperature, separating theliquid hydrocarbon from the suliuryl chloride solution and heating theliquid hydrocarbon to separate polymers 0! alkyl acetylene.

EGI V. FASCE.

